A Rio Outbound Short WF8F (315 grains) works great with a Ross Flystik especially when throwing some big uglies. When the rod was released, I tested the rod with that line. When fishing close in, just a bit more than a rod length of line off the tip top is needed to get the fly 25 to 30 feet out. With the whole head out, it turned the Flystik into a cannon.

Keep in mind that the Flystik is a short and fast rod. It was not meant for distance. It was made for accurate close in fishing. The rod can cast nearly the whole length of a Rio Outbound Short, but accuracy will not be that great.

An issue with the Rio Outbound Short is that it might be a spooky line for carp since it is oversized. You may want to use something lighter and finer. Since carp flies are not really big uglies, a WF9F SA Textured Magnum Taper or a Rio Coldwater Clouser Line may work better.

The reality is that you need to choose the line that will help you deliver the flies that you wish to present.